...don't forget that you need 161m of space around each stage. The stages can be as close together as you want, but each one needs to be at least 161m from other caches, stages, and finals. It's pretty saturated around these parts...
Actually, no. Section I.1.7. of the guidelines state (emphasis mine):
So this idea need not cover a lot of space.
I used to compete in road rallyes back in my college days. There are intentional "traps" where misinterpreting the rules or missing a landmark will send a car off course. Taking the wrong path results in a penalty in the form of the wrong time or the wrong answer to a question depending upon the type of the event. In a well-designed rallye, both (or all) possible paths converge so that a contestant does not know he goofed.
In the same manner, a multi-cache can have multiple paths ending up at the same final. Good luck explaining that to the reviewer...
One more thing. Dad and I used to argue over whether decoy caches are a good idea. He loved the idea of several containers with all but the real one bearing a message saying something like "try again." My position is that it was unnecessarily frustrating and invites the finder to insert a log into a decoy and claim a find. I bring this up because a stage can have more than one container, each one with different coordinates for the next stage, with the cacher "choosing" which path at random depending on which one is found.